You’ve probably heard the expression “black don’t crack,” a reference to black women’s ageless beauty. But though their skin may be smooth and wrinkle-free on the outside, black women are aging faster than white women on the inside, health experts say.

Dr. Michelle Gourdine, a former deputy secretary of health and chief public health physician for Maryland, explains that extreme stress causes wear and tear on our internal organs, contributing to heart disease, high blood pressure and stroke in black women—all diseases of aging. “The cells that make up your heart, your blood vessels, whatever else, begin to age prematurely because of all the stress, and that predisposes you to disease,” says Gourdine, author of Reclaiming Our Health: A Guide to African American Wellness.

She points to a 2010 National Institutes of Health study titled “Do US Black Women Experience Stress-Related Accelerated Biological Aging?” The study’s authors analyzed data from the Study of Women’s Health Across the Nation and found that black women between the ages of 49 and 55 are 7.5 years biologically “older” than white women